Laser radar telescope capable of adjusting power in real time and real-time power adjustment method

Abstract

The present application provides a laser radar telescope capable of adjusting power in real time and a method for adjusting power in real time. The laser radar telescope adopts a coaxial structure, uses a Cassegrain telescope as a receiving telescope, and sets a shaping mechanism between the receiving mirror group and the detection unit. The detection signal transmitted by the detection unit is received by the main control module, and a focal length adjustment signal is generated. The shaping mechanism adjusts the focal length of the optical path according to the focal length adjustment signal, so as to achieve the purpose of adjusting the laser power of the detection laser beam emitted by the transmitting module to reach the target to be measured in real time. Without adjusting the laser parameters, the present application uses the focal length adjustment function of the beam shaping mechanism to enable the laser power emitted or received by the laser radar telescope to be adjusted in real time according to the detection distance, taking into account the detection of near, medium and long distances, making up for the deficiency of the non-coaxial laser radar in the blind spot of close-range optical detection, and ensuring a high signal-to-noise ratio during close-range detection.

Description

Technical Field

[0001] The present invention relates to the field of laser radar technology, and in particular to a laser radar telescope capable of adjusting power in real time and a real-time power adjustment method. Background Art

[0002] LiDAR is an active detection system. Its working principle is to actively transmit laser signals to the target to be measured and receive the laser signals reflected back by the target. By comparing and analyzing the characteristics of the transmitted and received signals, the information of the target to be measured is obtained.

[0003] There are many detection principles for laser radar. The most widely used one is TOF (Time of Flight). Its principle is to use an ultra-short pulse laser to emit a short laser pulse to illuminate the target, detect the reflected light signal, and calculate the laser flight time based on the time difference between the measured pulse emission and the reflected pulse, thereby obtaining information such as the distance and / or contour of the target.

[0004] The current main applications of laser radar based on the TOF method are in two directions: close-range 3D scanning imaging and medium and long-distance ranging. In terms of medium and long-distance ranging, existing laser radars mostly use telescopes as the receiving end of reflected light. Benefiting from the high collimation of the laser itself, there is no need for beam shaping at the transmitting end. However, in practice, in order to solve the problem that the laser emitted by the laser has an increased degree of divergence at long distances, the divergence angle no longer meets the detection requirements. Therefore, the existing technology adds a beam shaping module to the rear end of the laser to compress the diameter of the light spot irradiated on the target; at the same time, the constraints that meet infinite distance imaging are added to the receiving end, so that it can meet the preset accuracy requirements when measuring at long distances.

[0005] However, it is precisely because the receiver adds the constraint of meeting infinite distance imaging that the detection accuracy of the receiver is greatly reduced during close-range detection. In order to achieve the detection accuracy of both close-range and medium- and long-range detection, in the prior art, some laser radar systems are equipped with long-range detection modules and short-range detection modules, which undoubtedly increases the design and manufacturing costs and also increases the size of the laser radar system. Summary of the invention

[0006] The present application proposes a laser radar telescope capable of adjusting power in real time and a real-time power adjustment method, which can solve the technical problem that the existing laser radar system cannot guarantee both short-range detection function and long-range detection accuracy.

[0007] In a first aspect, an embodiment of the present application provides a laser radar telescope capable of adjusting power in real time, comprising:

[0008] A transmitting module, used for transmitting a detection laser beam;

[0009] The receiving module comprises a receiving mirror group, a shaping mechanism and a detection unit; the receiving mirror group is used to receive and converge the echo signal of the detection laser beam reflected by the target to be detected; the detection unit is used to receive the echo signal transmitted by the receiving mirror group and generate a detection signal according to the echo signal;

[0010] Wherein, the detection laser beam passes through the shaping mechanism and the receiving mirror group in sequence to reach the target to be measured;

[0011] A main control module, electrically connected to the detection unit, and configured to receive and generate a focus adjustment signal according to the detection signal;

[0012] The shaping mechanism is arranged between the receiving lens group and the detection unit, and is electrically connected to the main control module; the shaping mechanism is used to receive and adjust the focal length of the optical path according to the focal length adjustment signal, so as to achieve real-time adjustment of the laser power of the detection laser beam reaching the target to be measured.

[0013] In some embodiments, the receiving mirror assembly includes a primary reflector and a secondary reflector, and the primary reflector and the secondary reflector are disposed opposite to and coaxially to form a Cassegrain telescope.

[0014] In some embodiments, the shaping mechanism is disposed in front of the focus of the secondary reflector.

[0015] In some embodiments, the shaping mechanism is an electric shaping mechanism, which is used to adaptively adjust the focal length according to the focal length adjustment signal.

[0016] In some embodiments, the shaping mechanism includes a positive focal length lens and a negative focal length lens coaxially arranged, and in the receiving light path, the negative focal length lens is located at the rear end of the positive focal length lens.

[0017] In some embodiments, the laser radar telescope also includes a beam splitting unit; the beam splitting unit is arranged on the output light path of the transmitting module and is coaxial with the receiving mirror group; the beam splitting unit is used to receive and split the detection laser beam and then reflect it to the receiving mirror group.

[0018] In some embodiments, the main control module includes a PID controller.

[0019] In some embodiments, the transmitting module includes a laser transmitter; and the detecting unit is a photodetector.

[0020] In a second aspect, an embodiment of the present application provides a method for real-time power adjustment of a laser radar telescope, which is applied to a laser radar telescope capable of real-time power adjustment as described in any of the above embodiments, and the method includes:

[0021] Configure initial parameters and aim the laser radar telescope at the target to be measured according to the position of the target to be measured;

[0022] Controlling the transmitting module to transmit a detection laser beam, and receiving an echo signal of the detection laser beam reflected by a target to be detected;

[0023] Acquire the detection signal generated by the detection unit according to the echo signal;

[0024] generating the focus adjustment signal according to the detection signal;

[0025] According to the focal length adjustment signal, the focal length of the shaping mechanism is adjusted in real time so that the signal detected by the detection unit meets the preset requirements.

[0026] In some embodiments, generating the focus adjustment signal according to the detection signal includes:

[0027] According to the detection signal and the current focal length of the optical path, the focal length of the optical path is adjusted based on the PID algorithm, and a focal length adjustment signal corresponding to the adjusted focal length is generated.

[0028] The embodiments of the present application provide a laser radar telescope with real-time adjustable power and a real-time power adjustment method. The laser radar telescope adopts a coaxial structure, uses a Cassegrain telescope as a receiving telescope, and arranges a shaping mechanism between the receiving mirror group and the detection unit. The main control module receives the detection signal transmitted by the detection unit and generates a focal length adjustment signal. The shaping mechanism adjusts the focal length of the optical path according to the focal length adjustment signal to achieve the purpose of real-time adjustment of the laser power of the detection laser beam emitted by the transmitting module to reach the target to be measured.

[0029] Without adjusting the laser parameters, the present application uses the focal length adjustment function of the beam shaping mechanism to adjust the laser power emitted or received by the laser radar telescope in real time according to the detection distance, taking into account the detection of near, medium and long distances, making up for the deficiency of the non-coaxial laser radar in the blind spot of close-range optical detection, and ensuring a high signal-to-noise ratio during close-range detection. At the same time, the laser radar system of the present application uses all conventional optical elements, without the need to process special-shaped structural elements or make holes in lenses or reflectors, which not only reduces the difficulty of processing and assembly, but also reduces the manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0031] Figure 1 A schematic diagram of the structure of a laser radar telescope capable of adjusting power in real time provided in an embodiment of the present application;

[0032] Figure 2 A schematic diagram of the structure of a laser radar telescope capable of adjusting power in real time provided by an embodiment of the present application;

[0033] Figure 3 A flowchart of a method for real-time power adjustment of a laser radar telescope provided in one embodiment of the present application.

[0034] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0036] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0037] The terms "first", "second", etc. in the specification and claims of this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable when appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are usually a class, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated before and after are in an "or" relationship. The "connection" and "connection" mentioned in this application, unless otherwise specified, include direct and indirect connections (connections).

[0038] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0039] Figure 1 This is a schematic diagram of the structure of a laser radar telescope capable of adjusting power in real time provided in an embodiment of the present application. Figure 1 As shown, the laser radar telescope with real-time adjustable power provided in the embodiment of the present application includes a transmitting module 110, a receiving module 120 and a main control module 130, and the transmitting module 110 and the receiving module 120 are coaxial systems and share a telescope.

[0040] When the laser radar telescope provided in this embodiment is transmission, its length is ≤500mm, the aperture is >Ф73mm, and the field of view angle is: 2w=80urad.

[0041] In this embodiment, the transmitting module 110 is used to transmit the detection laser beam, and the transmitting module 110 includes a laser transmitter, and the laser transmitter has a specific wavelength, and its specific parameters can be configured according to the detection accuracy. Generally, the laser transmitter is a high-power laser, which can be a 1550nm laser, and its laser pulse width is 10ns and the peak power is 20kW.

[0042] In some embodiments, the transmitting module also includes a beam expander. When the laser beam passes through the beam expander, its diameter will increase at a specific ratio. For example, the beam expander can have a beam expansion ratio of 20x. The laser beam is converted into parallel light (collimated light) through its lens to increase the transmission distance and focusing effect of the light beam.

[0043] The receiving module 120 includes a receiving mirror group 1201, a shaping mechanism 1202 and a detection unit 1203. The receiving mirror group 1201 is used to receive and converge the echo signal of the detection laser beam emitted by the transmitting module 110 and reflected by the target to be measured. The receiving mirror group 1201 is installed inside the telescope barrel at the rear end of the laser radar. The receiving mirror group 1201 includes a main reflector 12011 and a sub-reflector 12012, and the main reflector 12011 and the sub-reflector 12012 are arranged oppositely and coaxially to form a Cassegrain telescope.

[0044] The detection unit 1203 is used to obtain the echo signal transmitted by the receiving mirror group 1201 and generate a detection signal according to the echo signal. The detection laser beam passes through the shaping mechanism 1202 and the receiving mirror group 1201 in sequence to reach the target to be measured. The common detection unit 1203 can be a photodetector, for example, a CCD detector with a quantum noise of 10nW.

[0045] The main control module 130 is electrically connected to the detection unit 1203 and is used to receive and generate a focus adjustment signal according to the detection signal.

[0046] The shaping mechanism 1202 is arranged between the receiving lens group 1201 and the detection unit 1203, and the shaping mechanism 1202 is located in front of the focus of the secondary reflector 12012, and is electrically connected to the main control module 130. The shaping mechanism 1202 is used to receive and adjust the focal length of the optical path according to the focal length adjustment signal, so as to achieve the purpose of real-time adjustment of the laser power of the detection laser beam reaching the target to be measured.

[0047] In some embodiments, the adjustable focal length range of the shaping mechanism 1202 is: f=320±100mm.

[0048] In some embodiments, the shaping mechanism 1202 is an electric shaping mechanism, which is used to adaptively adjust the focal length according to a focal length adjustment signal.

[0049] Figure 2 This is a schematic diagram of the structure of a laser radar telescope capable of adjusting power in real time provided by an embodiment of the present application. Figure 2 As shown, the laser radar telescope with real-time power adjustment provided in the embodiment of the present application further includes a beam splitting unit 140 on the basis of the above embodiment. The beam splitting unit 140 is arranged on the output light path of the transmitting module 110 and is coaxial with the receiving lens group 1201; the beam splitting unit 140 is used to receive and split the detection laser beam and then reflect it to the receiving lens group 1201.

[0050] In some embodiments, the beam splitting unit 140 includes a beam splitter, and the reflection-transmission ratio of the beam splitter may be 1:1. The detection laser beam emitted by the laser transmitter is split and reflected by the beam splitter, and the reflected light enters the receiving lens group 1201 .

[0051] like Figure 2 As shown, in some embodiments, the primary reflector 12011 in the receiving mirror assembly 1201 is a parabolic mirror, the secondary reflector 12012 is a curved mirror, and the focal plane of the Cassegrain telescope is designed to be located between the parabolic primary mirror and the curved secondary mirror.

[0052] In some embodiments, the shaping mechanism 1202 includes a coaxially arranged positive focal length lens and a negative focal length lens, with focal lengths of f=100mm and f=-35mm respectively, and in the receiving light path, the negative focal length lens is located at the rear end of the positive focal length lens.

[0053] In some embodiments, the main control module 130 includes a PID controller, which can adjust the focal length of the optical path according to the acquired detection signal and the focal length of the current optical path to form an adaptive control closed loop, that is, according to the intensity of the light signal detected by the detection unit 1203, the focal length of the optical path is changed through the focusing function of the shaping mechanism 1202, and the laser power of the detection laser beam reaching the target to be measured is further changed, and finally the intensity of the light signal detected by the detection unit 1203 is changed so that it meets the requirements of detection accuracy, can take into account the detection of different distances, and has a wider range of use.

[0054] It should be noted that the PID controller is a powerful and flexible controller that plays an important role in industrial control systems. It is mainly composed of three parts: proportional unit (P), integral unit (I) and differential unit (D), and achieves precise control of the system by adjusting the three parameters of Kp (proportional coefficient), Ki (integral coefficient) and Kd (differential coefficient). Specifically, the PID controller collects real-time data from the system and compares it with the preset reference value to calculate the control error. Among them, the proportional unit (P) is used to directly output the control signal according to the size of the error, which is used to respond to the error quickly. The integral unit (I) performs an integral operation on the error to eliminate the steady-state error of the system. The differential unit (D) calculates the rate of change of the error to predict the future change of the error and make adjustments in advance, thereby improving the dynamic performance of the system. Compared with other simple control operations, the PID controller has better adaptability and robustness.

[0055] In this embodiment, a PID algorithm suitable for the laser radar telescope of the present application is preset in the PID controller. The control error can be calculated based on the detection signal acquired in real time and the focal length of the current optical path, and the focal length of the optical path is adjusted according to the error to form an adaptive control closed loop, that is, according to the intensity of the light signal detected by the detection unit 1203, the focal length of the optical path is changed through the focusing function of the shaping mechanism 1202, and the laser power of the detection laser beam reaching the target to be measured is further changed, thereby finally changing the intensity of the light signal detected by the detection unit 1203.

[0056] The working process of this embodiment is as follows: first, the detection laser beam emitted by the laser transmitter in the transmitting module 110 is split by the beam splitting unit 140, incident on the shaping mechanism 1202 after reflection, and transmitted to the secondary reflector 12012 in the receiving mirror group 1201 after shaping by the shaping mechanism 1202, and then reflected by the secondary reflector 12012 and the main reflector 12011 in turn, and then reaches the target to be measured; secondly, after being reflected by the target to be measured, an echo signal is formed, and the echo signal is received by the main reflector 12011 through the original optical path, and then passes through the main reflector 12011 and the secondary reflector in turn. The light is reflected by the mirror 12012, incident on the shaping mechanism 1202, transmitted through the shaping mechanism 1202 and the beam splitting unit 140 in sequence, converged, and reached the focal plane of the detection unit 1203, generating a detection signal; then, the main control module generates a focal length adjustment signal according to a preset corresponding algorithm based on the detection signal transmitted by the detection unit 1203, and transmits it to the shaping mechanism 1202, and the focal length adjustment can characterize the focal length of the optical path; finally, the shaping mechanism 1202 adjusts the focal length of the optical path in response to the focal length adjustment signal, thereby changing the laser power of the detection laser beam reaching the target to be measured.

[0057] In summary, the laser radar telescope with real-time power adjustment provided by the embodiment of the present application, without adjusting the laser parameters, can adjust the laser power emitted or received by the laser radar telescope in real time according to the detection distance by means of the focal length adjustment function of the beam shaping mechanism, taking into account the detection of near, medium and long distances, making up for the deficiency of the non-coaxial laser radar in the blind spot of close-range optical detection, and ensuring a high signal-to-noise ratio during close-range detection. At the same time, the laser radar system of the present application uses all conventional optical elements, without the need to process special-shaped structural elements or make holes in lenses or reflectors, which not only reduces the difficulty of processing and assembly, but also reduces the manufacturing cost.

[0058] Figure 3 This is a flow chart of a method for real-time power adjustment of a laser radar telescope provided in one embodiment of the present application. Figure 3 As shown, the laser radar telescope capable of adjusting power in real time according to any of the above embodiments, the steps of implementing real-time adjustment of output power specifically include:

[0059] Step S301, configure initial parameters, and aim the laser radar telescope at the target to be measured according to the direction of the target to be measured;

[0060] Step S302, controlling the transmitting module 110 to transmit a detection laser beam, and receiving an echo signal of the detection laser beam reflected by the target to be detected;

[0061] Step S303, the acquisition detection unit 1203 generates a detection signal according to the echo signal;

[0062] Step S304: generating a focus adjustment signal according to the detection signal;

[0063] In some embodiments, a focal length adjustment signal is generated according to the detection signal, which may be specifically: adjusting the focal length of the optical path based on a PID algorithm according to the detection signal and the current focal length of the optical path, and generating a focal length adjustment signal corresponding to the adjusted focal length.

[0064] Step S305: According to the focal length adjustment signal, the focal length of the shaping mechanism 1202 is adjusted in real time so that the signal detected by the detection unit 1203 meets the preset requirements.

[0065] It can be understood that before using the lidar telescope for detection, the initial parameters of the telescope system are first configured according to the detection accuracy requirements, and then the lidar telescope is aimed at the target to be measured according to the orientation of the target to be measured to start detection; during the detection process, according to the detected light signal intensity of the echo signal reflected by the target to be measured, the main control module generates a focal length adjustment signal corresponding to the adjusted focal length based on the preset PID algorithm, according to the current detected light signal intensity and the current focal length of the optical path, and then controls the shaping mechanism to adjust its own focal length to change the focal length of the current optical path, so that the laser power of the detection laser beam emitted by the transmitting module to the target to be measured is changed, and finally the signal detected by the detection unit meets the preset requirements, taking into account the detection of near, medium and long distances.

[0066] That is, without adjusting the laser parameters, the embodiment of the present application, with the help of the focal length adjustment function of the beam shaping mechanism, enables the laser power emitted or received by the lidar telescope to be adjusted in real time according to the detection distance, taking into account the detection of near, medium and long distances, making up for the deficiency of the non-coaxial lidar in the blind spot of close-range optical detection, and ensuring a higher signal-to-noise ratio during close-range detection.

[0067] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the inspiration of the present application, ordinary technicians in the field can make several simple deductions, deformations or substitutions based on the ideas of the present application without departing from the scope of protection of the purpose of the present application and the claims. All of these are within the protection of the present application.

Claims

1. A laser radar telescope capable of adjusting power in real time, characterized in that: include: A transmitting module, used for transmitting a detection laser beam; A receiving module, including a receiving mirror group, a shaping mechanism and a detection unit; The receiving mirror group is used to receive and converge the echo signal of the detection laser beam reflected by the target to be measured; the detection unit is used to receive the echo signal transmitted by the receiving mirror group, and generate a detection signal according to the echo signal; wherein the detection laser beam passes through the shaping mechanism and the receiving mirror group in sequence to reach the target to be measured; A main control module, including a PID controller; the main control module is electrically connected to the detection unit, and is used to receive and adjust the focal length of the optical path based on the PID algorithm according to the detection signal, and generate a focal length adjustment signal corresponding to the adjusted focal length; The shaping mechanism is arranged between the receiving lens group and the detection unit, and is electrically connected to the main control module; the shaping mechanism is used to receive and adjust the focal length of the optical path according to the focal length adjustment signal, so as to achieve real-time adjustment of the laser power of the detection laser beam reaching the target to be measured; The shaping mechanism comprises a positive focal length lens and a negative focal length lens which are coaxially arranged, and in the receiving light path, the negative focal length lens is located at the rear end of the positive focal length lens; the adjustable focal length range of the shaping mechanism is: f=320±100mm.

2. The laser radar telescope capable of adjusting power in real time according to claim 1, characterized in that: The receiving mirror group includes a main reflector and a secondary reflector, and the main reflector and the secondary reflector are arranged opposite to each other and coaxially to form a Cassegrain telescope.

3. The laser radar telescope capable of adjusting power in real time according to claim 2, characterized in that: The shaping mechanism is arranged in front of the focus of the secondary reflector.

4. The laser radar telescope capable of adjusting power in real time according to claim 3, characterized in that: The shaping mechanism is an electric shaping mechanism, which is used for adaptively adjusting the focal length according to the focal length adjustment signal.

5. The laser radar telescope capable of adjusting power in real time according to claim 1, characterized in that: It also includes a beam splitting unit; the beam splitting unit is arranged on the outgoing light path of the transmitting module and is coaxial with the receiving mirror group; the beam splitting unit is used to receive and split the detection laser beam and then reflect it to the receiving mirror group.

6. The laser radar telescope capable of adjusting power in real time according to claim 1, characterized in that: The transmitting module includes a laser transmitter; the detecting unit is a photoelectric detector.

7. A method for real-time power adjustment of a laser radar telescope, applied to a laser radar telescope capable of real-time power adjustment as claimed in any one of claims 1 to 6, characterized in that: include: Configure initial parameters and aim the laser radar telescope at the target to be measured according to the position of the target to be measured; Controlling the transmitting module to transmit a detection laser beam, and receiving an echo signal of the detection laser beam reflected by a target to be detected; Acquire the detection signal generated by the detection unit according to the echo signal; generating the focus adjustment signal according to the detection signal; According to the focal length adjustment signal, the focal length of the shaping mechanism is adjusted in real time so that the signal detected by the detection unit meets the preset requirements.

8. The method for real-time power adjustment of a laser radar telescope according to claim 7, characterized in that: The step of generating the focus adjustment signal according to the detection signal comprises: According to the detection signal and the current focal length of the optical path, the focal length of the optical path is adjusted based on the PID algorithm, and a focal length adjustment signal corresponding to the adjusted focal length is generated.

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